Research

Since the inception of the nano bull, the ultrafast laser-induced two-photon polymerization technique has found widespread application in complex structure 3D printing. However, a significant challenge faced by this technology is its limited applicability to organic materials such as photosensitive polymers, rendering it unsuitable for inorganic materials like semiconductors or metal oxides. Previous efforts attempted to blend precursors of inorganic materials with photosensitive polymers or relied on materials like glass or hydrogels as mechanical support matrices. They utilized the printability or patternability of polymers to achieve hybrid material systems with complex 3D structures. However, in these hybrid materials, the proportion of inorganic materials was typically low (usually less than 20% by weight), making it difficult to showcase the intrinsic properties and functionalities of the inorganic materials.

To address this, Prof. Hong-Bo Sun proposed a new principle of photo-excitation-induced chemical bonding (Science 377, 1112, 2022). Subsequently, in further research, he utilized inorganic colloidal nanocrystals as building blocks for the respective inorganic materials. Through non-specific photochemical cross-linking reactions between surface ligands, stable covalent bonds were formed among different nanocrystals. This development led to a universally applicable new chemistry and technology for 3D printing of inorganic materials. Without the need for templates or supporting materials like photosensitive resins, this approach achieves arbitrary 3D structures with nanoscale precision, high inorganic content (approaching nearly 100% by weight), and high mechanical strength (Science 381, 1468, 2023).

The aforementioned achievements were reported by dozens of internationally renowned academic media outlets such as Laser Focus World and were selected as one of the 30 significant advancements in Optics & Photonics News in 2023 globally. They were also recognized as one of the Top 10 Progresses in Chinese Optics in 2022 and one of the Top 10 Socially Influential Events in Chinese Optics in 2022.